But although the coal trade was fairly extensive for that period, it was utterly insignificant compared with its present dimensions, and that for a very good reason. There was no means of pumping water out of the mines, except by the old-fashioned air-pump, which was of course utterly inadequate. Nor was a suitable invention discovered till the very end of the seventeenth century, when Thomas Savery in 1698 invented a kind of pump, worked by the condensation of steam. This rather clumsy invention, however, was soon superseded in 1705 by Newcomen’s steam pump. But it was not till after the commencement of the Industrial Revolution that steam power was scientifically applied to coal-mines by the inventions of Watt and Boulton (1765 and 1774), which we shall notice in their proper place. Up to that time, also, it was difficult to transport coal into inland districts by road, Newcastle coal being carried to London in ships, and then carried up inland rivers in barges. But these barges could not go high up many rivers at that time, and canals were not yet made. It was difficult for instance to get coal to Oxford, for it had to come to London, and then part way up the Thames, which was not then navigable so far. But at Cambridge it was easily procurable, for barges could come right up to the town from eastern ports. Hence it was much cheaper at Cambridge than at Oxford. § 7. THE IRON TRADE—As it had been with coal, so with iron. Only very small quantities of it were mined in the {139} Middle Ages; it was smelted only by wood, as a rule, and was manufactured only in a very rude way. We saw that at the great fairs foreign iron, chiefly from the Biscay coast, was much in demand, as our own supply was utterly insufficient. It was naturally not until we learnt to mine and use our coal properly that we learnt also how to mine and manufacture our iron. Before learning this, English workmen used wood as fuel, and it is to this cause that we owe the destruction of most of the forests which, at the time of Domesday, occupied so large an area. “The waste and destruction of the woods in the counties of Warwick, Stafford, Hereford, Monmouth, Gloucester, and Salop by these iron-works is not to be imagined,” a speaker said in Parliament as late as the beginning of the eighteenth century. And as wood was used as house-fuel also, it will readily be understood what a vast destruction of timber took place. In 1581 the erection of iron-works within certain distances from London and the Thames was prohibited “for the preservation of the woods.”